One technique for recovering hydrocarbons (also referred to as producing hydrocarbons or hydrocarbon production) from a hydrocarbon-bearing formation involves the drilling of a wellbore into the hydrocarbon-bearing formation and pumping the hydrocarbons, such as oil, out of the formation. In many cases, however, the oil is too viscous under the formation conditions, and thus adequate oil flow rates cannot be achieved with this technique.
Radio frequency antennas have been utilized to heat the viscous oil and reduce its viscosity. For example, numerous investigators have published research results on using electromagnetic methods to produce the hydrocarbons from the hydrocarbon-bearing formation. However, the application of electromagnetic methods to subsurface formations has generally been plagued by uneven heating, including excessive heating, near the wellbore, which may lead to damage to the wellbore, damage to the radio frequency antenna, or any combination thereof.
Some attention has been paid to the problem of non-uniform heating by electromagnetic methods. For example, U.S. Pat. No. 5,293,936 attempted to resolve the uneven heating problem when using a monopole or dipole antenna-like apparatus by modifying edge and power input regions to purportedly achieve equal distribution of electric fields. U.S. Pat. No. 7,312,428 suggested switching out different electrode element pairs for moments of time or possibly providing different field strengths to different portions of the formation or stratification to achieve more uniform heating of the formation. Each of these patents is incorporated by reference in its entirety.
Bientinesi et al. (M. Bientinesi, L. Petarca, A. Cerutti, M. Bandinelli, M. De Simoni, M. Manotti, G. Maddinelli, J. Pet. Sci. Eng., 107, 18-30, 2013), which is incorporated by reference in its entirety, carried out experimental work and numerical simulation of radio frequency (RF)/microwave (MW) heating using quartz sand as a low RF absorbance material. The authors heated oil-containing sand to 200° C. using a dipolar radio frequency antenna irradiating at 2.45 GHz. Their lab and modelling results showed that the presence of the quartz sand around the antenna lowered the temperature in this critical zone and better distributed the irradiated energy in the oil sand. However, the use of sand or other similar porous solids alone as low RF absorbance material do not work properly because of their tendency to become water-wet during the days and months of dielectric heating. An increase of water saturation leads to an increase in the RF absorption properties which, in turn, may still lead to excessive heating causing damage to the wellbore, damage to the radio frequency antenna, or any combination thereof.
There is still a need for an improved manner of using a radio frequency antenna for hydrocarbon recovery that addresses the excessive heating challenge.